In the related art, for example, an LED bulb (lamp apparatus) having a cap which is mountable in a socket for general lighting bulbs is provided with a resin or metallic housing having a cap mounting portion to which the cap is fixed on one end side thereof. Then, the LED bulb includes alighting apparatus accommodated in the interior of the housing and an LED module (light-emitting body) mounted on the other end side of the housing. Provided on an outer peripheral surface of the housing are thermal radiating fins for radiating heat generated by the LED module or the lighting apparatus. A globe configured to cover the LED module as needed is attached to the other end side of the housing.
The LED module generates heat in association with lighting of LEDs. The heat rises the temperature of the LEDs. Then, when the temperature of the LEDs is excessively high, light-emitting efficiency of the LEDs is lowered, and a problem such as reduction of lifespan of the LEDs may occur. Therefore, the housing is provided with a thermal radiating device configured to radiate heat generated by the LED module from the thermal radiating fins to an outside space.
Examples of the LED bulb include the one configured in such a manner that an outer peripheral edge portion side of the LED module is fixed to an annular mounting surface of the housing, and the lighting apparatus is accommodated in a void of the housing (for example, see Patent Document 1). According to the LED bulb described above, the heat generated by the LED module is conducted from the annular mounting surface to the housing and radiated to the outside space from the thermal radiating fins.
There is also an LED bulb of a type in which the LED module is placed on a flat-shaped light source supporting portion of the housing and is disposed in tight contact therewith so as to allow thermal conduction (for example, see Patent Document 2). According to the LED bulb described above, the heat generated by the LED module is transferred to the light source supporting portion which is in tight-contact with the LED module and is radiated effectively from the housing to the outside space via the thermal radiating fins.
The configuration in which the outer peripheral edge portion side of the LED module is fixed to the annular mounting surface of the housing allows the heat generated by the LED module to be conducted mainly from the outer peripheral edge portion side of the LED module to the mounting surface of the housing. Therefore, the heat can hardly be conducted quickly to the housing side. Therefore, the above-described configuration is disadvantageous in that inhibition of temperature rise of the LEDs with respect to a high-power and high-output LED module is difficult.
The configuration in which the LED module is placed on the flat-shaped light source supporting portion of the housing and is brought into tight contact therewith allows the heat generated by the LED module to be conducted quickly to the housing and to be radiated from the thermal radiating fins because the contact surface area between the LED module and the light source supporting portion is large. However, since the portion of the light source supporting portion is formed on a mass of the housing, the configuration in this example is disadvantageous in that a space for disposing the lighting apparatus can hardly be secured and the weight of the housing is increased. In particular, when the housing is formed of a metal, the weight may pose a problem.